From 7 to 7½ weeks, tendons attach leg muscles to bones, and knee joints appear.
Also by 7½ weeks, the hands can be brought together, as can the feet.
The embryo also kicks, and will jump if startled.
Also by 7 to 7½ weeks, nephrons, the basic filtration units in the kidneys, begin to form.
Seven Week Image:
![7 Weeks](https://www.babychris.org/images/scale-7wks-sm.png)
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